Sonic tool with means for reducing noise level



Dec. 2, 1969 J. w. WOOD SONIC TOOL WIT H MEANS FOR REDUCING NOISE LEVEL Filed Feb. 19, 1968 TRANSDUCER SONIC TOOL SOUND INSULATING MATERIAL FIG. 2

LEAD SHEET FOAMED PLASTIC INVENTOR JOHN W. WOOD ATTORNEY United States Patent 3,481,411 SONIC TOOL WITH MEANS FOR REDUCING NOISE LEVEL John W. Wood, Baltimore, Md., assignor to The Black and Decker Manufacturing Company, Towson, Md., a corporation of Maryland Filed Feb. 19, 1968, Ser. No. 706,353

Int. Cl. E21b 1/06, 7/04; B25d 17/04 US. Cl. 173-117 9 Claims ABSTRACT OF THE DISCLOSURE A sonic tool houses a resonant transducer which is adapted for delivering energy to a work-engaging tool element. The transducer exhibits cyclic elastic deformations within the sonic acoustical range. A layer of sound insulating material is provided within the housing for substantially reducing the ambient noise level externally of the sonic tool.

OBJECTS OF THE DISCLOSURE It is an object of the present invention to substantially reduce the ambient noise level externally of a sonic tool for improved safety and comfort for the operator.

It is another object to provide a layer of sound insulating material arranged against the inner surfaces of the housing for a sonic tool.

It is yet another object to provide a layer of sound insulating material for substantially enclosing the piezoelectric transducer of a sonic tool.

It is a further object to incorporate, within a sonic tool, a layer of sound insulation comprising two layers of foamed plastic with a lead sheet therebetween.

These and other objects of the present invention will become apparent from a reading of the following specification taken in conjunction with the enclosed drawings.

DESCRIPTION OF THE DRAWINGS FIGURE 1 is a side elevation of a portable sonic hand tool, with certain parts broken away and sectioned, illustrating one embodiment of the present invention;

FIGURE 2 is a second embodiment, wherein the layer of sound insulating material is joined to the inner surface of the walled housing substantially throughout the sonic tool; and

FIGURE 3 is an enlargement of a portion of FIGURE 2, showing a preferred form of sound insulating material.

DETAILED DESCRIPTION With reference to FIGURE 1, there is illustrated a portable sonic (or ultrasonic) hand tool 10 having a generally longitudinal housing 11 within which a resonant means comprising a transducer assembly 12 is disposed. Any type of transducer assembly or means may be employed, but preferably the transducer assembly 12 is of the piezoelectric type and exhibits cyclic elastic deformations within the sonic acoustical range, such as 10,000 cycles per second, during the operation of the tool. Moreover, the construction and theory of operation of the transducer assembly 12 form no part of the present invention, but rather are described more specifically in the McMaster et al. Patent No. 3,368,085, entitled Sonic Transducer, issued on Feb. 6, 1968.

With this in mind, the transducer assembly 12 comprises an intermediate substantially acoustically-nodal portion 13 secured to the housing as at 14, a pair of piezoelectric transducer crystals or elements 15, a contact ring or element 16 between the transducer elements, a spacer portion 17, a mechanical impedance-transforming horn portion 18 formed integrally with the nodal portion and ex- 3,481 ,41 l Patented Dec. 2, 1969 tending forwardly therefrom, a central bolt portion 19 formed integrally with the nodal portion and extending rearwardly therefrom, the transducer elements and the contact element being piloted on the bolt and electrically insulated therefrom, and nut means 20 engaging the central bolt for retaining the overall assembly and for applying the desired degree of axial compressive bias upon the transducer elements. This compressive clamping of the transducer elements is habitually resorted to in the prior art and is illustrated in the now-expired patents to Heising, No. 2,044,000, and to Burkhardt, No. 2,368,609.

The portable sonic tool 10 further includes a pistol-grip handle 21 adapted to be grasped by the operator for applying the tool to the work W. In lieu of the pistol-grip configuration, any suitable handle means may be provided, or else the tool housing itself could be grasped by the operator. A trigger 22 is provided for controlling the energization of the tool from a line cord 23, and it will be noted that the electrical connections, being conventional, have been omitted for ease of illustration.

A tool element 24 is provided, which tool element may comprise a masonry-drilling bit, a wood-gouging tool, a scraping blade, or any suitable type of work-engaging element; and preferably, the tool element 24 is loosely (or removably) mounted within a bearing sleeve 25 (or its equivalent) on the housing. The tool element 24 includes a first portion 24A extending within the tool housing, confronting the end face 18-A of the horn portion 18 of the transducer assembly, and adapted to receive a series of vibratory-type impacts therefrom during the operation of the tool. The tool element further includes a collar portion 24B which is in abutting engagement with the forward face of the tool housing. Moreover, the impact-receiving portion 24A is axially positioned with respect to the impact-delivering horn portion 18 of the transducer assembly by a predetermined amount. This amount, in one embodiment, comprises only a few thousandths of an inch; while in another embodiment, the surfaces are just touching each other.

With this arrangement, the forward thrust or bias is exerted by the operator on the handle 21, through the housing 11 to the collar 24B on the tool element 24, and through the tool element directly to the work. Thus, any variations or excesses or operator bias are in a sense neutralized; hence are precluded from overloading the transducer and otherwise interfering with the transducer output or efficiency. The construction of the sonic tool 10 and its method of operation are described in detail in the copending Riley et al. application, Ser. No. 705,045, filed February 13, 1968, entitled Portable Sonic Hand Tool with Means for Reducing the Effects of Operator Bias Upon Transducer Output and Efficiency, and assigned to the assignee of the present invention.

With further reference to FIGURE 1, a layer 26 of I hesive) to the inner surface of the walled housing 11, from the intermediate nodal portion 13 of the transducer assembly 12 to the rearward extremity of the tool.

In the embodiment of FIGURE 2, a similar layer 27 of sound insulating material is joined to the inner surface of the walled housing substantially throughout the sonic tool.

The preferred material, with which the improved results have been obtained, is shown in enlarged cross-section in FIGURE 3. The layer (26 or 27) comprises a first layer 28 of foamed plastic against the inner surface of the housing wall, a relatively-thin lead sheet 29 against the other side of the first plastic layer 28, and a second layer 30 of foamed plastic on the other side of the lead sheet. Preferably, the second plastic layer 30 is somewhat thicker than the first layer 28.

Thus the layer (26 or 27) substantially encloses the transducer, especially the piezoelectric transducing elements 15, and has been found in practice to substantially reduce the ambient noise level externally of the sonic tool, thereby materially improving the safety, comfort and convenience to the operator of the sonic tool as well as others in the vicinity. In laboratory testing of an embodiment similar to that of FIGURE 2, approximately a decibel reduction in sound (or noise) energy level was obtained.

Obviously, many modifications may be made without departing from the basic spirit of the present invention; and accordingly, within the scope of the appended claims, the invention may be practiced other than has been specifically described herein.

I claim:

1. In a sonic tool having a walled housing, a workengaging tool element adjacent said housing, a transducer of the piezoelectric type within said housing, said transducer having an intermediate, substantially nodal portion mounted to the housing and further having an impedancetransforming horn portion forwardly of said nodal portion for delivering vibratory energy to said tool element, said transducer exhibiting cyclic elastic deformations within the sonic acoustical range, and sound insulating material mounted within said housing for substantially reducing the ambient noise level externally of said tool, said material comprising a layer of sound-damping material of high density and low stilfness suspended between two layers of sound-absorbent material having low density and low stifl'ness.

2. The sonic tool of claim 1, wherein the sound insulating material comprises a layer joined to the inner surface of the walled housing from the intermediate nodal portion of the transducer to the rearward extremity of the tool.

3. The sonic tool of claim 1, wherein the sound insulating material comprises a layer joined to the inner surface of the walled housing substantially throughout the sonic tool.

4. The sonic tool of claim 1 wherein said sound-damping layer comprises lead and wherein said sound absor- Ibent material comprises plastic.

5. In a sonic tool having a housing, a work-engaging tool element adjacent to the housing, a transducer within the housing for delivering vibratory energy within the sonic acoustical range to the tool element, and a layer of.

sound insulating material within the housing for substantially reducing the ambient noise level externally of the sonic tool, thereby improving operator safety and convenience, said layer of sound insulating material comprising two layers of plastic with a relatively-thin lead sheet therebetween.

6. In a sonic tool having a walled housing, a workengaging toolelement adjacent said housing, a transducer of the piezoelectric type Within said housing, the transducer having an intermediate substantially-nodal portion mounted to the housing and further having an impedancetransforming horn portion forwardly of its nodal portion for delivering vibratory energy to the tool element, the transducer exhibiting cyclic elastic deformations within the sonic acoustical range, and sound insulating material within said housing comprising a first layer of foamed plastic against the inner surface of the walled housing, a relatively-thin lead sheet against the other side of said first plastic layer, and a second layer of foamed plastic on the other side of the lead sheet.

7. In a portable sonic tool having a walled housing, handle means adapted to be grasped by an operator for applying the tools to a workpiece, a transducer mounted Within said housing, said transducer exhibiting cyclic elastic deformations within the sonic acoustical range, and a layer of sound insulating material joined to the inner surface of said walled housing and enclosing at least a portion of said transducer to reduce the ambient noise level externally of said tool, said sound insulating material comprising a layer of sound-damping material enclosed between two layers of sound-absorbent material.

8. A portable sonic tool as claimed in claim 7 wherein said sound damping material comprises lead and wherein said sound absorbent material comprises a flexible plastic.

9. In an impact tool having a housing, a work-engaging tool element adjacent to the housing, a transducer Within the housing for delivering vibratory energy within the sonic acoustical range to the tool element, and a layer of sound insulating material within the housing for substantially reducing the ambient noise level externally of the impact tool, thereby improving operator safety and convenience, said layer of sound insulating material comprising two layers of sound-absorbent material with a sounddampening material therebetween.

References Cited UNITED STATES PATENTS JAMES A. LEPPINK, Primary Examiner US. Cl. XJR. 

